Global demand for linear alkylbenzene sulfonates (LAS) is 6.7 billion lb/yr (“The Future of LAB” Amandeep Singh, Inform Magazine AOCS, March 2012) with 2.7% demand growth. Alkylbenzene sulfonates, especially those made from linear alkylbenzenes (LAB), are primary surfactants used in household cleaners and detergents. The demand for linear alkyl benzene sulfonates continues to grow because of their low cost, strong performance, and biodegradability.
A limitation to increased use of LAS surfactants and related linear surfactants has been because they have poor solubility in cold water and hard water conditions (US 2012/0213726 and WO 2012/138423). This is supported by J. Scheibel in Journal of Surfactants and Detergents, (2004) 7, 319, which reported the 4-, 5-, and 6-PhLAS isomers are sensitive to calcium, which form aggregates and are less surface active than the 2-PhLAS and 3-PhLAS isomers. Also J. Scheibel reported that the 2-PhLAS surface activity (critical micelle concentration (CMC)) was 600 ppm while 3-PhLAS CMC was 700 ppm, under the same conditions. Therefore, it takes 15% less of the 2-PhLAS isomer to form a micelle compared to the 3-PhLAS isomer. This aligns well with the publicly communicated “green” initiatives of major detergent companies such as Proctor & Gamble, which by 2020 seeks a 20% reduction in packaging compared to 2010 levels, and a 20% reduction in truck transportation compared to 2010 levels (http://www.pg.com/en_US/sustainability/environmental_sustainability/environmental_vision.shtml as accessed on Apr. 9, 2013).
One of the “holy grails” of the detergent industry is more concentrated cleaning power. Many industrial experts have described the superior cleaning performance of the 2-PhLAS isomer over the other LAS isomers (e.g., the 1-, 3-, 4-, 5- and 6-PhLAS). U.S. Pat. No. 6,887,839 describes high 2-PhLAS mixtures are more effective cleaning agents over their counterparts with lower 2-PhLAS isomeric content, this is attributed to an unexpected increase in tolerance of water hardness minerals usually associated with precipitation of the active detergent agent. Further fine-tuning of cleaning performance of 2-PhLAS-based agents may be achieved by substitution of additional functional groups on the aromatic ring. For example, 2-tolyl linear alkylbenzene sulfonates have been reported to have lower Krafft temperatures and superior hard water tolerance compared to commercial linear alkylbenzene sulfonate materials (U.S. Pat. No. 6,995,127).
There are two currently used commercial production processes for LAS. The first, the HF alkylation of detergent (C10-C13) olefins, gives 18% of the 2-PhLAB isomer while the second, the Detal™ process (licensed by UOP), uses a zeolite catalyst to alkylate detergent olefins and produces 25-35% of 2-PhLAB (Zoller, U. “Handbook of Detergents: Part F Production,” v. 142, CRC Press, Boca Raton, Fla., 2009, p 111). It is estimated that ˜80% of current manufacturers use the HF process, but new capacity is typically based upon the Detal™ process which also enjoys lower capital costs. It is important to point out that both the HF and Detal™ processes have little control over the formation of the 2-PhLAB isomer as these processes are Friedel-Craft type alkylation of the aromatic ring with an olefin. Under these conditions the double bond of the olefin is isomerized (i.e. migrated along its backbone) resulting in positional-isomeric mixtures of PhLAB. (e.g. 1-PhLAB, 2-PhLAB, 3-PhLAB, 4-PhLAB, 5-PhLAB, 6-PhLAB, etc.).
Over the years efforts have been made to increase the concentration of 2-PhLAS isomer content over other LAS isomers. For example, U.S. Pat. No. 6,562,776 describes a mixture of salts of alkylbenzene sulfonates, prepared by the HF process, wherein the 2-phenyl isomer content of such alkylbenzene sulfonate salts is 42%-82% by weight based on the total weight of LAS isomers.
U.S. Pat. No. 6,887,839 is incorporated by reference and describes high content 2-phenyl linear alkyl benzene sulfonates having enhanced hard water tolerance. This patent does not produce 2-phenyl linear alkylbenzene sulfonates in >85% isomeric purity and does not describe olefin metathesis to produce 2-phenyl linear alkylbenzene sulfonates.
U.S. Pat. App. Pub. No 2012/0213726 is incorporated by reference and describes bio-based linear alkyl phenyl sulfonates (linear alkylbenzene sulfonates) incorporating C10-C14 olefins which at least 50% bio-based. The bio-based C10-C14 olefins may be produced by metathesis of seed oils as described in U.S. Pat. App. Pub. No US2010/0145086. U.S. Pat. App. Pub. No. 2012/0213726 does not describe olefin metathesis of alpha-methyl styrene or 3-phenyl-1-butene to produce linear alkyl phenyl sulfonates (linear alkylbenzene sulfonates).
WO Pat. App. Pub. No. 2012/138423 is incorporated by reference and describes C10-C13 linear alkyl phenyl sulfonates (linear alkylbenzene sulfonates) having a particular alkyl group distribution. This application describes using a particular C10-C13 olefin distribution to produce C10-C13 linear alkyl phenyl sulfonates (linear alkylbenzene sulfonates). It does not describe olefin metathesis of alpha-methyl styrene or 3-phenyl-1-butene to produce linear alkyl phenyl sulfonates (linear alkylbenzene sulfonates).
U.S. Pat. App. Pub. No. 2010/0145086 is incorporated by reference and is the seminal patent application describing the production of alpha olefins from alkenolysis of seed oils. It does not describe olefin metathesis of alpha-methyl styrene or 3-phenyl-1-butene to produce linear alkyl benzenes, linear 2-phenylalkylbenzenes, linear alkyl phenyl sulfonates, or linear alkylbenzene sulfonates.
U.S. Pat. No. 6,995,127 is incorporated by reference and describes relatively high content 2-tolyl linear alkyl benzene sulfonates having enhanced hard water tolerance. This patent does not produce 2-phenyl linear alkylbenzene sulfonates in >85% isomeric purity and does not describe olefin metathesis to produce 2-phenyl linear alkylbenzene sulfonates. Under the HF and Detal™ processes utilized, the resulting 2-tolyl linear alkyl benzene sulfonates predominantly comprise para-tolyl groups due to the ortho/para directing effects of methyl(alkyl) groups (combined with steric effects which disfavor ortho-substitution). Similarly, electron-withdrawing groups (i.e. NO2, CN, etc.) would yield predominantly meta-substituted isomers. In contrast, the methods described herein would allow for controlled substitution at any particular position of the aromatic ring or any desired combination of these positions. For example, commercially available tolylstyrenes are available as a mixture of approximately 60% meta- and 40% para-methyl substitution, which will produce a 2-tolyl linear alkylbenzene sulfonate with the same 60% meta- and 40% para-methyl substitution, or in a nearly pure para-methyl form.
Therefore, despite advances achieved in the art, a continuing need exists for further improvement in a number of areas, including methods for the production of alkylbenzenes and alkylbenzene sulfonates having improved selectivity of 2-phenyl linear alkylbenzene isomer production as well as compositions comprising improved 2-phenyl linear alkylbenzene isomer content. In addition, despite advances achieved in the art, a continuing need exists for further improvement in a number of areas, including methods for the production of substituted alkylbenzenes and substituted alkylbenzene sulfonates having improved selectivity of substituted 2-phenyl linear alkylbenzene isomer production as well as compositions comprising improved substituted 2-phenyl linear alkylbenzene isomer content, where the benzene ring is substituted with one or more groups designated R*, where R* is defined herein.